You are more likely to get some joy from talking to the landlord. Might be worth popping round to let them know your plans, and point out to them that post-uni they will likely be looking to rent elsewhere, and the first point of contact for a reference is the previous landlord.
why would you contact the landlord? the guy's done nothing, his mates did but he got in touch with them and got them to come round. tbf he's done everything you'd expect him to and now you want to grass to his landlord. what more do you expect either the guy or the landlord to do? unless of course the landlord's a windscreen repair man in which case call him
Four reasons.
Firstly, its an extra point of leverage. Maybe they've had other complaints and will bottle it when they realise they could get their lease terminated and pay up the £95.
Assuming it goes beyond that and they don't pay up...
Secondly, because the guys did it while they were visiting his premise. I'd say there was a moral obligation on the neighbour to get this sorted.
Thirdly, because the stronger the reaction this time, the less likelihood there is of it happening again. Their course could easily have another couple of years to run so they could be neighbours for quite a while.
Fourthly, because Josedinho already told them that's what he was thinking of doing so all he is doing is playing straight and making clear he isn't going to be messed around.
If they don't like it, well, fuck them. They are the ones with the idiot friends. I don't see how you can say he's done everything you'd expect him to do. First he denied having mates round. When that was exposed as a lie he basically phoned them, accepted their denial, shrugged his shoulders and said 'case closed'.
One man's grass is another man's law abiding citizen.
I've rented out a couple of flats in the past, and the contract terms these days are pretty draconian. For example in the contract I use, the following clause if breached is sufficient to allow the landlord to give notice to the tenant..
"12.1 The Tenant shall not (nor allow others to) cause nuisance or annoyance to the Landlord, other tenants or any neighbours."
I don't want any tenants who cause grief for the neighbours. it's bad for me, bad for the neighbours, and bad for prices. If I were the landlord in this case and it was a first offence I'd tell them if it happened again they were out, and I'd definitely pressure them to pay up for the damages.